Left hand ramps are frowned upon by highway engineers due to the safety problem posed by having people merge into the fast lane when they're entering the freeway, but in 2011, Gilbert Chlewicki, the man who invented the diverging diamond interchange (or rather reinvented it after France tried it and gave up on it in the 70s, decided to defend the undefendable.
(https://divergingdiamond.com/blog/reconsidering-left-side-ramps-on-freeways/)
Quote
Cost Savings — Left exits can easily save $50-$100 Million (or more) on a construction project for major interchanges. The reason is that left exits are more direct than right exits, which means less land is needed for the interchange as a whole and expensive fly-over ramps with long bridges can be avoided.
Lane Balancing — When all ramps are on the right side of the highway, it requires a heavier load of traffic in the right lanes of the highway. When an interchange has a high volume of traffic using the ramps, this can cause delays on the entire highway due to the heavy weaving needed that slows traffic down. When left ramps are introduced, traffic can be more evenly distributed among all the lanes of the highway, which can improve overall traffic flow.
Thru Lane Continuity — When there is a high volume of traffic for the off-ramps, it is often necessary to peel one of the thru lanes of the highway into the ramp. For instance, suppose 1,500 vehicles/hr want to go onto a westbound ramp and another 1,500 vehicles/hr want to go onto an eastbound ramp. If, as suggested by the AASHTO Policy on Geometric Design (the Green Book), we have one ramp on the right for both movements, followed by a split on that ramp, we would require at least two lanes of traffic on the initial off-ramp. For smooth traffic flow, this would likely require one of the thru lanes on the highway to be peeled off to the ramp. If a left exit were introduced for one of those movements, no consideration would be needed to convert a highway thru lane into a ramp lane.
Elimination of Weaving Concerns within the Interchange — The simplest interchange form which requires no intersections within the interchange is the full cloverleaf. But the cloverleaf is an inefficient and often unsafe form due to the short weaving concerns. Many cloverleaf interchanges are being converted into other interchange forms to eliminate the weaving. Left side ramps are very efficient at avoiding weaving issues within the interchange.
And they still build them today. They used them on the Tip O'Neill tunnel because it allows entrances and exits to be neatly tucked into the Rose Kennedy Greenway, whereas if they had used right hand ramps, they would've had to demolish several buildings to make space for the portals. And in Santa Clara County, they want to grade separate the Lawrence Expressway using left hand exit and entrance ramps (https://countyroads.sccgov.org/sites/g/files/exjcpb681/files/Lawrence%20Expy%20Study%20093014%20noappendices%20lowres.pdf). And with driverless cars, the safety problems could disappear, so maybe this will become much more common.
I think left exits and entrances can be okay. Like any interchange design, it just needs to be designed and built properly. If you don't have enough room for acceleration/deceleration, the ramp will be sketchy no matter what side of the highway it's on. Many of us know how bad EB I-69 to SB I-75 in Michigan is because of a complete lack of acceleration space despite being on the right.
The one thing I think we can almost all agree on is the terrible concept that full cloverleaves are on anything beyond the most minor of traffic volumes. I'd rather have left exits than cloverleaves, as long as the design is decent and there's ample warning the exit is on the left.
DDIs are solid interchanges IMO.
I recognize he's not talking solely about DDIs and is instead talking about left-side ramps in general, but in the DDI context I would argue that left-side ramps in a standard DDI are a different circumstance anyway because the "fast lane" (more properly the "passing lane") is not an issue, as the road with the left-side ramps is, by definition, not going to be a freeway due to there being traffic lights at either end of the DDI where the directions cross over. If there were to be a modified DDI that used grade-separated crossovers to eliminate the two traffic lights, that might be a different scenario.
I didn't click your link (don't have time), but one problem I've noted with left-side ramps in general-purpose lanes (as opposed to managed lanes, which generally carry fewer vehicles) is that it exacerbates the incredibly annoying tendency some people have to camp in the left lane. "I want to exit on the left six miles down the road, so I'm going to get over to the left lane immediately." Ugh.
Quote from: JoePCool14 on February 26, 2021, 09:19:22 AM
I think left exits and entrances can be okay. Like any interchange design, it just needs to be designed and built properly. If you don't have enough room for acceleration/deceleration, the ramp will be sketchy no matter what side of the highway it's on. Many of us know how bad EB I-69 to SB I-75 in Michigan is because of a complete lack of acceleration space despite being on the right.
The one thing I think we can almost all agree on is the terrible concept that full cloverleaves are on anything beyond the most minor of traffic volumes. I'd rather have left exits than cloverleaves, as long as the design is decent and there's ample warning the exit is on the left.
DDIs are solid interchanges IMO.
Don't get me started on cloverleaves. I have to use the i-93/i-95 one in Reading to get to work. It's not so bad now but a year ago, before the pandemic it was a nightmare.
Quote from: 1995hoo on February 26, 2021, 09:21:54 AM
I recognize he's not talking solely about DDIs and is instead talking about left-side ramps in general, but in the DDI context I would argue that left-side ramps in a standard DDI are a different circumstance anyway because the "fast lane" (more properly the "passing lane") is not an issue, as the road with the left-side ramps is, by definition, not going to be a freeway due to there being traffic lights at either end of the DDI where the directions cross over. If there were to be a modified DDI that used grade-separated crossovers to eliminate the two traffic lights, that might be a different scenario.
I didn't click your link (don't have time), but one problem I've noted with left-side ramps in general-purpose lanes (as opposed to managed lanes, which generally carry fewer vehicles) is that it exacerbates the incredibly annoying tendency some people have to camp in the left lane. "I want to exit on the left six miles down the road, so I'm going to get over to the left lane immediately." Ugh.
I can definitely see that being a problem. If you don't give enough advanced noticed, it's confusing. But if you give too much advanced notice, people camp in the left lane. As with all things there's never a one size fits all solution.
I will say that in urban and suburban areas, for instance the Tri-State in Chicagoland, there's so much traffic that all lanes are filled with cars. Yes, the slower traffic generally stays on the right, but it's rare to get an open left lane. In that instance, a left exit with campers wouldn't make things much worse than they already are.
Quote from: JoePCool14 on February 26, 2021, 09:49:29 AM
I will say that in urban and suburban areas, for instance the Tri-State in Chicagoland, there's so much traffic that all lanes are filled with cars. Yes, the slower traffic generally stays on the right, but it's rare to get an open left lane. In that instance, a left exit with campers wouldn't make things much worse than they already are.
Here's the catch, though: You need people to keep right even when traffic is light, that way things keep moving for as long as possible and don't jam up as quickly. Sure, it might be so busy that it doesn't matter at 8 AM, but when people don't care about keeping right at 5 AM, it starts to hold up the faster traffic and slow the whole system down as it gets busier.
It seems to me that the problems caused by left hand ramps is solely due to them not being normal. If they were the norm then the rightmost lane would be the fast lane and the problem goes away. I wonder why they chose right hand ramps in the first place.
Quote from: kernals12 on February 26, 2021, 09:45:32 AM
Quote from: JoePCool14 on February 26, 2021, 09:19:22 AM
I think left exits and entrances can be okay. Like any interchange design, it just needs to be designed and built properly. If you don't have enough room for acceleration/deceleration, the ramp will be sketchy no matter what side of the highway it's on. Many of us know how bad EB I-69 to SB I-75 in Michigan is because of a complete lack of acceleration space despite being on the right.
The one thing I think we can almost all agree on is the terrible concept that full cloverleaves are on anything beyond the most minor of traffic volumes. I'd rather have left exits than cloverleaves, as long as the design is decent and there's ample warning the exit is on the left.
DDIs are solid interchanges IMO.
Don't get me started on cloverleaves. I have to use the i-93/i-95 one in Reading to get to work. It's not so bad now but a year ago, before the pandemic it was a nightmare.
That's because of the lane drop at Route 28, not because of the cloverleaf.
Don't left entrances almost always have yield signs posted on them?
Quote from: interstatefan990 on February 26, 2021, 10:36:27 AM
Don't left entrances almost always have yield signs posted on them?
Not the ones that I've seen.
Quote from: kernals12 on February 26, 2021, 09:56:43 AM
It seems to me that the problems caused by left hand ramps is solely due to them not being normal. If they were the norm then the rightmost lane would be the fast lane and the problem goes away. I wonder why they chose right hand ramps in the first place.
This makes it sound like you're advocating for driving on the left, like in the UK. That would be fine with me, aside from the obvious practical problems of having to replace all the road signs and traffic lights and then having over 99 percent of the cars on the road having the steering wheels on the wrong side. I've driven on the left in the UK and I never had any issues with it.
But from the summary of the article you posted, I construed the writer's point as being that there should not necessarily be a preference for having exit ramps on either particular side, whether the right or the left, and that instead they should just go where it seems most appropriate in a given situation. From your comment quoted above, it sounds like you're suggesting left-side ramps should be the standard and right-side ramps should be the exception. I don't think that makes any sense for a variety of reasons. One obvious one is the outside ramps in a cloverleaf (i.e., the "non-loop" ramps)–it makes complete sense to have those exactly where they are on the right side because that is the shortest distance for that maneuver and it requires the least amount of construction. Even if I accept the idea that left-side ramps may sometimes be desirable or preferable–and I think I can accept that premise in certain road configurations–that doesn't mean right-side ramps should be the "exception," rather than the norm, in countries where you drive on the right.
Quote from: JoePCool14 on February 26, 2021, 10:42:03 AM
Quote from: interstatefan990 on February 26, 2021, 10:36:27 AM
Don't left entrances almost always have yield signs posted on them?
Not the ones that I've seen.
Only 2 'left' entrances I know of in the Pgh area that have a yield sign for them: https://goo.gl/maps/mXiPXKSgzPsS3r2s9 https://goo.gl/maps/GsseTe581iGmSii27
Quote from: 1995hoo on February 26, 2021, 10:53:00 AM
Quote from: kernals12 on February 26, 2021, 09:56:43 AM
It seems to me that the problems caused by left hand ramps is solely due to them not being normal. If they were the norm then the rightmost lane would be the fast lane and the problem goes away. I wonder why they chose right hand ramps in the first place.
This makes it sound like you're advocating for driving on the left, like in the UK. That would be fine with me, aside from the obvious practical problems of having to replace all the road signs and traffic lights and then having over 99 percent of the cars on the road having the steering wheels on the wrong side. I've driven on the left in the UK and I never had any issues with it.
But from the summary of the article you posted, I construed the writer's point as being that there should not necessarily be a preference for having exit ramps on either particular side, whether the right or the left, and that instead they should just go where it seems most appropriate in a given situation. From your comment quoted above, it sounds like you're suggesting left-side ramps should be the standard and right-side ramps should be the exception. I don't think that makes any sense for a variety of reasons. One obvious one is the outside ramps in a cloverleaf (i.e., the "non-loop" ramps)–it makes complete sense to have those exactly where they are on the right side because that is the shortest distance for that maneuver and it requires the least amount of construction. Even if I accept the idea that left-side ramps may sometimes be desirable or preferable–and I think I can accept that premise in certain road configurations–that doesn't mean right-side ramps should be the "exception," rather than the norm, in countries where you drive on the right.
But given the context, you should clearly be able to tell that I'm not advocating for driving on the left. That ability to draw on previous knowledge to figure out somewhat ambiguous situations is a key part of human intellect, one which AI engineers envy.
If you enter on the left and exit on the right at the next exit, or the inverse, you'll have to change several lanes quickly.
Quote from: rickmastfan67 on February 26, 2021, 10:58:59 AM
Quote from: JoePCool14 on February 26, 2021, 10:42:03 AM
Quote from: interstatefan990 on February 26, 2021, 10:36:27 AM
Don't left entrances almost always have yield signs posted on them?
Not the ones that I've seen.
Only 2 'left' entrances I know of in the Pgh area that have a yield sign for them: https://goo.gl/maps/mXiPXKSgzPsS3r2s9 https://goo.gl/maps/GsseTe581iGmSii27
If you look at I-244 in Tulsa, OK, you'll see several of its left entrances have yield signs.
https://goo.gl/maps/6vy5A7D3YHTxLxHn8
https://goo.gl/maps/BJo7CrNDCjXnsFYx8
https://goo.gl/maps/4BBqZEAe3n32m35Q7
Quote from: kernals12 on February 26, 2021, 11:00:12 AM
Quote from: 1995hoo on February 26, 2021, 10:53:00 AM
Quote from: kernals12 on February 26, 2021, 09:56:43 AM
It seems to me that the problems caused by left hand ramps is solely due to them not being normal. If they were the norm then the rightmost lane would be the fast lane and the problem goes away. I wonder why they chose right hand ramps in the first place.
This makes it sound like you're advocating for driving on the left, like in the UK. That would be fine with me, aside from the obvious practical problems of having to replace all the road signs and traffic lights and then having over 99 percent of the cars on the road having the steering wheels on the wrong side. I've driven on the left in the UK and I never had any issues with it.
But from the summary of the article you posted, I construed the writer's point as being that there should not necessarily be a preference for having exit ramps on either particular side, whether the right or the left, and that instead they should just go where it seems most appropriate in a given situation. From your comment quoted above, it sounds like you're suggesting left-side ramps should be the standard and right-side ramps should be the exception. I don't think that makes any sense for a variety of reasons. One obvious one is the outside ramps in a cloverleaf (i.e., the "non-loop" ramps)–it makes complete sense to have those exactly where they are on the right side because that is the shortest distance for that maneuver and it requires the least amount of construction. Even if I accept the idea that left-side ramps may sometimes be desirable or preferable–and I think I can accept that premise in certain road configurations–that doesn't mean right-side ramps should be the "exception," rather than the norm, in countries where you drive on the right.
But given the context, you should clearly be able to tell that I'm not advocating for driving on the left. That ability to draw on previous knowledge to figure out somewhat ambiguous situations is a key part of human intellect, one which AI engineers envy.
Correct, but you did refer to the right lane becoming what you call the "fast lane" (I assume you mean to refer to the passing lane). That's a hallmark of countries where you drive on the left–the right lane is the passing lane there because the traffic patterns are essentially reversed from what they are here. As an aside, the weird California practice of referring to lanes by number would make a lot more sense in a country where you drive on the left because the lane numbers would be in the proper order going left to right. But I digress. That particular part of your comment stood out to me because it seems you are suggesting there should be some sort of complete reversal in traffic patterns, and I found that to be rather preposterous on the whole
unless you were to advocate completely switching sides of the road.
If you don't mean that, then I will reiterate that one problem with not having consistency as to which side the exits and entrances are on would mean that there would really be no predictability as to what should be the "passing lane" (or, as some people erroneously call it, the "fast lane"). You'd have people merging into traffic, and both accelerating and decelerating, on both sides. On a highway with three lanes in each direction, would that mean that the center lane should be the passing lane? "Keep Right or Left Except to Pass"? On a highway with two lanes in each direction, there would be no "passing lane" (due to regular exits on both sides) and the result would invariably be the need for a lot more lane-changing, which most authorities agree is one of the things that leads to more accidents, and in turn more congestion due to the accidents, blockages, rubbernecking, etc.
Despite your condescending reply, I'm not trying to attack you (this time)–rather, I'm trying to carry your comments out to explore the consequences of what would happen if the idea were implemented.
Quote from: 1 on February 26, 2021, 11:01:28 AM
If you enter on the left and exit on the right at the next exit, or the inverse, you'll have to change several lanes quickly.
This was a long-time problem on the Beltway in Virginia when the I-66 interchange, which is less than a mile north of the next interchange to the south and about two miles south of the next one to the north, had a left-side exit and entrance on the Inner Loop and people cut across four lanes of traffic to get to and from those ramps.
Also, despite the comment below from ari-s-drives, this was not necessarily a situation of short trips because I-66 carries a lot of longer-distance traffic and the next exit to the north is a major business district (Tysons Corner).
Quote from: 1 on February 26, 2021, 11:01:28 AM
If you enter on the left and exit on the right at the next exit, or the inverse, you'll have to change several lanes quickly.
Looking at the source, the DDI guy says that this could discourage making short trips by freeway rather than surface streets.
Quote from: Gilbert Chlewicki
The second issue discussed was heavy lane shifting. This is a legitimate concern when two interchanges are closely spaced. When this happens, there are still ways to mitigate the weaving concern. A barrier can be placed in the highway that prohibits dangerous weaving from one ramp to the next. Drivers who would have made that weave but are now prohibited can be suggested an alternate route or be provided with an additional left side ramp to make the movement safely.
...
Left side ramps could provide a possible benefit by discouraging very short trips on the highway that can be done with the local network. Imagine if each interchange on a highway alternated with left side ramps and right side ramps with barriers between the interchanges that would prohibit drivers to weave between adjacent interchanges. This could improve the operations of the highway significantly and make better use of our full roadway network.
Quote from: 1995hoo on February 26, 2021, 11:23:59 AM
Quote from: kernals12 on February 26, 2021, 11:00:12 AM
Quote from: 1995hoo on February 26, 2021, 10:53:00 AM
Quote from: kernals12 on February 26, 2021, 09:56:43 AM
It seems to me that the problems caused by left hand ramps is solely due to them not being normal. If they were the norm then the rightmost lane would be the fast lane and the problem goes away. I wonder why they chose right hand ramps in the first place.
This makes it sound like you're advocating for driving on the left, like in the UK. That would be fine with me, aside from the obvious practical problems of having to replace all the road signs and traffic lights and then having over 99 percent of the cars on the road having the steering wheels on the wrong side. I've driven on the left in the UK and I never had any issues with it.
But from the summary of the article you posted, I construed the writer's point as being that there should not necessarily be a preference for having exit ramps on either particular side, whether the right or the left, and that instead they should just go where it seems most appropriate in a given situation. From your comment quoted above, it sounds like you're suggesting left-side ramps should be the standard and right-side ramps should be the exception. I don't think that makes any sense for a variety of reasons. One obvious one is the outside ramps in a cloverleaf (i.e., the "non-loop" ramps)–it makes complete sense to have those exactly where they are on the right side because that is the shortest distance for that maneuver and it requires the least amount of construction. Even if I accept the idea that left-side ramps may sometimes be desirable or preferable–and I think I can accept that premise in certain road configurations–that doesn't mean right-side ramps should be the "exception," rather than the norm, in countries where you drive on the right.
But given the context, you should clearly be able to tell that I'm not advocating for driving on the left. That ability to draw on previous knowledge to figure out somewhat ambiguous situations is a key part of human intellect, one which AI engineers envy.
Correct, but you did refer to the right lane becoming what you call the "fast lane" (I assume you mean to refer to the passing lane). That's a hallmark of countries where you drive on the left–the right lane is the passing lane there because the traffic patterns are essentially reversed from what they are here. As an aside, the weird California practice of referring to lanes by number would make a lot more sense in a country where you drive on the left because the lane numbers would be in the proper order going left to right. But I digress. That particular part of your comment stood out to me because it seems you are suggesting there should be some sort of complete reversal in traffic patterns, and I found that to be rather preposterous on the whole unless you were to advocate completely switching sides of the road.
If you don't mean that, then I will reiterate that one problem with not having consistency as to which side the exits and entrances are on would mean that there would really be no predictability as to what should be the "passing lane" (or, as some people erroneously call it, the "fast lane"). You'd have people merging into traffic, and both accelerating and decelerating, on both sides. On a highway with three lanes in each direction, would that mean that the center lane should be the passing lane? "Keep Right or Left Except to Pass"? On a highway with two lanes in each direction, there would be no "passing lane" (due to regular exits on both sides) and the result would invariably be the need for a lot more lane-changing, which most authorities agree is one of the things that leads to more accidents, and in turn more congestion due to the accidents, blockages, rubbernecking, etc.
Despite your condescending reply, I'm not trying to attack you (this time)–rather, I'm trying to carry your comments out to explore the consequences of what would happen if the idea were implemented.
Quote from: 1 on February 26, 2021, 11:01:28 AM
If you enter on the left and exit on the right at the next exit, or the inverse, you'll have to change several lanes quickly.
This was a long-time problem on the Beltway in Virginia when the I-66 interchange, which is less than a mile north of the next interchange to the south and about two miles south of the next one to the north, had a left-side exit and entrance on the Inner Loop and people cut across four lanes of traffic to get to and from those ramps.
Also, despite the comment below from ari-s-drives, this was not necessarily a situation of short trips because I-66 carries a lot of longer-distance traffic and the next exit to the north is a major business district (Tysons Corner).
I mean that if left hand ramps were the norm, then for safety reasons, the passing lane would be the right lane for the same reason that the left lane is the passing lane in our world where right hand ramps are the norm
Quote from: kernals12 on February 26, 2021, 11:31:44 AM
I mean that if left hand ramps were the norm, then for safety reasons, the passing lane would be the right lane for the same reason that the left lane is the passing lane in our world where right hand ramps are the norm
But based on the article summary you posted, it seems the writer there is not advocating making left-side ramps "the norm" (a phrase I understand to mean "the ordinary practice" or "the preferred practice," i.e., the standard, such that in this case right-side ramps would be "the exception"). You included a reference to "lane balancing" in the quote box in your original post, and it refers to traffic being more "evenly distributed." That implies both left- and right-side ramps.
There's space to put ramps on the outside of a freeway. It's much harder to put ramps on the inside.
Quote from: kernals12 on February 26, 2021, 11:31:44 AM
Quote from: kernals12 on February 26, 2021, 09:56:43 AM
It seems to me that the problems caused by left hand ramps is solely due to them not being normal. If they were the norm then the rightmost lane would be the fast lane and the problem goes away. I wonder why they chose right hand ramps in the first place.
...
I mean that if left hand ramps were the norm, then for safety reasons, the passing lane would be the right lane for the same reason that the left lane is the passing lane in our world where right hand ramps are the norm
OK, so aren't you really wondering why
left hand ramps were chosen in the first place, not right hand ones?
Quote from: interstatefan990 on February 26, 2021, 11:13:47 AM
Quote from: rickmastfan67 on February 26, 2021, 10:58:59 AM
Quote from: JoePCool14 on February 26, 2021, 10:42:03 AM
Quote from: interstatefan990 on February 26, 2021, 10:36:27 AM
Don't left entrances almost always have yield signs posted on them?
Not the ones that I've seen.
Only 2 'left' entrances I know of in the Pgh area that have a yield sign for them: https://goo.gl/maps/mXiPXKSgzPsS3r2s9 https://goo.gl/maps/GsseTe581iGmSii27
If you look at I-244 in Tulsa, OK, you'll see several of its left entrances have yield signs.
https://goo.gl/maps/6vy5A7D3YHTxLxHn8
https://goo.gl/maps/BJo7CrNDCjXnsFYx8
https://goo.gl/maps/4BBqZEAe3n32m35Q7
I think those have yield signs because of how short the acceleration space is. Here's a couple that I know of that do not have them.
https://goo.gl/maps/HeqcnW42XJzGQcwj8 (https://goo.gl/maps/HeqcnW42XJzGQcwj8)
https://goo.gl/maps/xSRSj5WLaPojzLpM8 (https://goo.gl/maps/xSRSj5WLaPojzLpM8)
Quote from: webny99 on February 26, 2021, 11:36:51 AM
Quote from: kernals12 on February 26, 2021, 11:31:44 AM
Quote from: kernals12 on February 26, 2021, 09:56:43 AM
It seems to me that the problems caused by left hand ramps is solely due to them not being normal. If they were the norm then the rightmost lane would be the fast lane and the problem goes away. I wonder why they chose right hand ramps in the first place.
...
I mean that if left hand ramps were the norm, then for safety reasons, the passing lane would be the right lane for the same reason that the left lane is the passing lane in our world where right hand ramps are the norm
OK, so aren't you really wondering why left hand ramps were chosen in the first place, not right hand ones?
Yes I am. Frankly I think it's superior from the standpoint of cost and right of way requirements.
Quote from: 1 on February 26, 2021, 11:35:45 AM
There's space to put ramps on the outside of a freeway. It's much harder to put ramps on the inside.
Most freeways have wide medians
Quote from: kernals12 on February 26, 2021, 12:03:57 PM
Quote from: 1 on February 26, 2021, 11:35:45 AM
There's space to put ramps on the outside of a freeway. It's much harder to put ramps on the inside.
Most rural freeways have wide medians
FTFY. I cannot think of a single urban freeway in either the Salt Lake or Atlanta area (the two metros I frequent most) with big enough medians to fit new left-exit ramps in.
The "median" on most urban freeways I drive usually amounts to a tall concrete barrier.
Quote from: US 89 on February 26, 2021, 12:06:52 PM
Quote from: kernals12 on February 26, 2021, 12:03:57 PM
Quote from: 1 on February 26, 2021, 11:35:45 AM
There's space to put ramps on the outside of a freeway. It's much harder to put ramps on the inside.
Most rural freeways have wide medians
FTFY. I cannot think of a single urban freeway in either the Salt Lake or Atlanta area (the two metros I frequent most) with big enough medians to fit new left-exit ramps in.
I-93 has a good sized median north of Boston.
Quote from: kernals12 on February 26, 2021, 12:11:05 PM
Quote from: US 89 on February 26, 2021, 12:06:52 PM
Quote from: kernals12 on February 26, 2021, 12:03:57 PM
Quote from: 1 on February 26, 2021, 11:35:45 AM
There's space to put ramps on the outside of a freeway. It's much harder to put ramps on the inside.
Most rural freeways have wide medians
FTFY. I cannot think of a single urban freeway in either the Salt Lake or Atlanta area (the two metros I frequent most) with big enough medians to fit new left-exit ramps in.
I-93 has a good sized median north of Boston.
I'm not seeing anything near wide enough to put a ramp until you get into New Hampshire, with the exception of a short segment just north of MA 125 that doesn't have any cross streets to interchange with.
Quote from: 1 on February 26, 2021, 12:14:21 PM
Quote from: kernals12 on February 26, 2021, 12:11:05 PM
Quote from: US 89 on February 26, 2021, 12:06:52 PM
Quote from: kernals12 on February 26, 2021, 12:03:57 PM
Quote from: 1 on February 26, 2021, 11:35:45 AM
There's space to put ramps on the outside of a freeway. It's much harder to put ramps on the inside.
Most rural freeways have wide medians
FTFY. I cannot think of a single urban freeway in either the Salt Lake or Atlanta area (the two metros I frequent most) with big enough medians to fit new left-exit ramps in.
I-93 has a good sized median north of Boston.
I'm not seeing anything near wide enough to put a ramp until you get into New Hampshire, with the exception of a short segment just north of MA 125 that doesn't have any cross streets to interchange with.
The most common reason for using left hand ramps is to reduce ROW requirements. A combined northbound exit and southbound entrance ramp will take up less space than if they used separate ones.
Quote from: US 89 on February 26, 2021, 12:06:52 PM
The "median" on most urban freeways I drive usually amounts to a tall concrete barrier.
On some stretches of freeway where I drive, it's literally just a guardrail.
Well, understand that highways are built with ramp locations in mind. You are all looking at *existing* highways that don't have space in the median for ramps. Build a new highway from scratch, and you could much more easily design it with ramps in the median, vs on the right.
Quote from: jeffandnicole on February 26, 2021, 01:34:23 PM
Well, understand that highways are built with ramp locations in mind. You are all looking at *existing* highways that don't have space in the median for ramps. Build a new highway from scratch, and you could much more easily design it with ramps in the median, vs on the right.
Or modify a highway, for that matter. The I-495 HO/T lanes in Virginia use almost entirely left-side ramps, with a few exceptions in the Tysons Corner area. That was a case of an existing road that generally had no median being rebuilt into a wider road that still has no median but has the express lanes down the middle with their ramps shoehorned in. (In a sense, it was similar to how it would be if the Jersey Turnpike's "dual-dual" format were extended all the way to the southern terminus, but the "inner drive" ramps were constructed on the left instead of on the right. Not a perfect analogy, but similar conceptually.)
With that said, not surprisingly the OP still hasn't responded to my point about the "passing lane" problem.
What about left exits that lead to a freeway-to-freeway ramp? You could theoretically exit left and then have a flyover/other ramp to a normal right-side merge. I imagine it would be much more costly to construct a right-side exit ramp for certain layouts of freeways, like where the other road is far left of the original one. I'm sure there are real-life examples of this.
BTW, I can think of a place where left- and right-side onramps enter at essentially the same location: https://goo.gl/maps/55VDBhN3LkKZ2wAC7
(https://www.aaroads.com/forum/proxy.php?request=http%3A%2F%2Fupload.wikimedia.org%2Fwikipedia%2Fcommons%2F7%2F75%2FPulaski_Skyway_Kearny_ramp.jpg&hash=34ad560ea656aacf13945bfd13b1fb14dabc74fd)
Sexy.
Quote from: 1995hoo on February 26, 2021, 02:18:58 PM
Quote from: jeffandnicole on February 26, 2021, 01:34:23 PM
Well, understand that highways are built with ramp locations in mind. You are all looking at *existing* highways that don't have space in the median for ramps. Build a new highway from scratch, and you could much more easily design it with ramps in the median, vs on the right.
Or modify a highway, for that matter. The I-495 HO/T lanes in Virginia use almost entirely left-side ramps, with a few exceptions in the Tysons Corner area. That was a case of an existing road that generally had no median being rebuilt into a wider road that still has no median but has the express lanes down the middle with their ramps shoehorned in. (In a sense, it was similar to how it would be if the Jersey Turnpike's "dual-dual" format were extended all the way to the southern terminus, but the "inner drive" ramps were constructed on the left instead of on the right. Not a perfect analogy, but similar conceptually.)
With that said, not surprisingly the OP still hasn't responded to my point about the "passing lane" problem.
Actually I did respond
Quote from: kernals12 on February 26, 2021, 11:31:44 AM
I mean that if left hand ramps were the norm, then for safety reasons, the passing lane would be the right lane for the same reason that the left lane is the passing lane in our world where right hand ramps are the norm
I'm not entire sure it would. On two-lane roads, one would still pass on the left. It would be a strange situation in which
pass on the left is the norm on some highways but
pass on the right is the norm on others. Strange enough that it might not even develop.
Quote from: kernals12 on February 26, 2021, 02:56:19 PM
Quote from: 1995hoo on February 26, 2021, 02:18:58 PM
Quote from: jeffandnicole on February 26, 2021, 01:34:23 PM
Well, understand that highways are built with ramp locations in mind. You are all looking at *existing* highways that don't have space in the median for ramps. Build a new highway from scratch, and you could much more easily design it with ramps in the median, vs on the right.
Or modify a highway, for that matter. The I-495 HO/T lanes in Virginia use almost entirely left-side ramps, with a few exceptions in the Tysons Corner area. That was a case of an existing road that generally had no median being rebuilt into a wider road that still has no median but has the express lanes down the middle with their ramps shoehorned in. (In a sense, it was similar to how it would be if the Jersey Turnpike's "dual-dual" format were extended all the way to the southern terminus, but the "inner drive" ramps were constructed on the left instead of on the right. Not a perfect analogy, but similar conceptually.)
With that said, not surprisingly the OP still hasn't responded to my point about the "passing lane" problem.
Actually I did respond
Actually, you didn't.
I don't really have an issue with left exits, given they're adequately signed. Heck, right exits can be problematic if they aren't signed well in advance. Years ago, I was traveling in Tennessee on I-81 and was unable to exit because the first exit sign was a 1-mile advance, I was in the left lane passing trucks, and there was not a suitable gap in traffic for me to get over to the right lane until I was right at the exit. So I had to go to the next exit and backtrack on surface routes, which was more of a minor annoyance than a terrible inconvenience.
But left entrances ... aargh. The two I probably hate most are I-66 west onto I-81 south, and the infamous Poughkeepsie "bowtie."
Poughkeepsie bowtie would have worked well...if traffic volumes hadn't climbed. I like that interchange. :D
From an article about the Illinois DOT (https://www.oakpark.com/2011/01/11/idot-hopes-to-eliminate-oak-parks-left-side-ramps-on-the-eisenhower/)'s plans to remove Oak Park's infamous left exits
Quote"Even highway exits go to the left in Oak Park," goes the old joke. In 1961, Oak Park's then-village president J. Russell Christianson lobbied hard to get left-hand exits when the "Congress Expressway" was built, seeking to decrease loss of property and noise levels. The name of the expressway changed to the "Eisenhower," but the ramps stayed on the left.
And here's an example of the difference in ROW requirements
Normal: https://countyroads.sccgov.org/sites/g/files/exjcpb681/files/Central%20Expy_Lafayette_Alt%201.pdf
Left Exit and Entrance: https://countyroads.sccgov.org/sites/g/files/exjcpb681/files/Central%20Expy_Lafayette_Alt%202.pdf
This layout creates what is basically a SPUI interchange, with all the associated traffic benefits and at a lower cost at that.
Quote from: kernals12 on February 26, 2021, 09:56:43 AM
It seems to me that the problems caused by left hand ramps is solely due to them not being normal. If they were the norm then the rightmost lane would be the fast lane and the problem goes away. I wonder why they chose right hand ramps in the first place.
This. Imagine how easier it would be to plan and design highways if the left lanes were the slow/merge lanes and all highways exited to the inside lanes rather than the outside lanes. No dual signalization at on-and-off ramps. Every freeway entrance would effectively be a SPUI. And expanding left turn capacity for entering a freeway wouldn't impact signal timing or the effectiveness of the corresponding offramp. And imagine how much less right of way would be needed to expand freeways at crossroads.
Wouldn't the interchanges cost more to construct, though? At a traditional diamond, only the crossroad needs to have a bridge. If the ramps connect to it midway, then they need to be overhead as well.
Quote from: Occidental Tourist on February 26, 2021, 11:30:28 PM
And imagine how much less right of way would be needed to expand freeways at crossroads.
Now imagine the headache of expanding the
ramps, though.
If the road changes from freeway to expressway, the slow lane would need to switch from the left to the right.
Quote from: kphoger on February 27, 2021, 08:24:11 AM
Quote from: Occidental Tourist on February 26, 2021, 11:30:28 PM
And imagine how much less right of way would be needed to expand freeways at crossroads.
Now imagine the headache of expanding the ramps, though.
But since it would be a SPUI, the ramps would have more capacity and would be less likely to need expansion.
Quote from: kphoger on February 27, 2021, 08:23:25 AM
Wouldn't the interchanges cost more to construct, though? At a traditional diamond, only the crossroad needs to have a bridge. If the ramps connect to it midway, then they need to be overhead as well.
You could use embankment.
Quote from: kernals12 on February 26, 2021, 10:29:16 PM
From an article about the Illinois DOT (https://www.oakpark.com/2011/01/11/idot-hopes-to-eliminate-oak-parks-left-side-ramps-on-the-eisenhower/)'s plans to remove Oak Park's infamous left exits
Quote"Even highway exits go to the left in Oak Park," goes the old joke. In 1961, Oak Park's then-village president J. Russell Christianson lobbied hard to get left-hand exits when the "Congress Expressway" was built, seeking to decrease loss of property and noise levels. The name of the expressway changed to the "Eisenhower," but the ramps stayed on the left.
And here's an example of the difference in ROW requirements
Normal: https://countyroads.sccgov.org/sites/g/files/exjcpb681/files/Central%20Expy_Lafayette_Alt%201.pdf
Left Exit and Entrance: https://countyroads.sccgov.org/sites/g/files/exjcpb681/files/Central%20Expy_Lafayette_Alt%202.pdf
This layout creates what is basically a SPUI interchange, with all the associated traffic benefits and at a lower cost at that.
And those left exits are terrible pieces of shit (having to pass them virtually every workday). They clog up the Ike in the area due to vehicles cutting left to exit at both Austin and Harlem. And then they clog from slow-moving traffic entering on the left. The Oak Park section should've been built with proper service drives and right-hand exits.
Quote from: Brandon on February 27, 2021, 08:43:04 AM
Quote from: kernals12 on February 26, 2021, 10:29:16 PM
From an article about the Illinois DOT (https://www.oakpark.com/2011/01/11/idot-hopes-to-eliminate-oak-parks-left-side-ramps-on-the-eisenhower/)'s plans to remove Oak Park's infamous left exits
Quote"Even highway exits go to the left in Oak Park," goes the old joke. In 1961, Oak Park's then-village president J. Russell Christianson lobbied hard to get left-hand exits when the "Congress Expressway" was built, seeking to decrease loss of property and noise levels. The name of the expressway changed to the "Eisenhower," but the ramps stayed on the left.
And here's an example of the difference in ROW requirements
Normal: https://countyroads.sccgov.org/sites/g/files/exjcpb681/files/Central%20Expy_Lafayette_Alt%201.pdf
Left Exit and Entrance: https://countyroads.sccgov.org/sites/g/files/exjcpb681/files/Central%20Expy_Lafayette_Alt%202.pdf
This layout creates what is basically a SPUI interchange, with all the associated traffic benefits and at a lower cost at that.
And those left exits are terrible pieces of shit (having to pass them virtually every workday). They clog up the Ike in the area due to vehicles cutting left to exit at both Austin and Harlem. And then they clog from slow-moving traffic entering on the left. The Oak Park section should've been built with proper service drives and right-hand exits.
You're further proving my point that the only real problem with left hand ramps is that they're unfamiliar to drivers. I imagine that tomorrow's driverless cars will be programmed to smoothly move across the freeway in anticipation of left hand exit ramps and cooperate so that left hand entrance ramps don't cause traffic snarls.
Quote from: GaryV on February 27, 2021, 08:34:42 AM
If the road changes from freeway to expressway, the slow lane would need to switch from the left to the right.
I guess it would be instinctive, drivers would quickly figure out that the slow lane is the one with all the exits and entrances.
Quote from: kernals12 on February 27, 2021, 08:50:42 AM
Quote from: GaryV on February 27, 2021, 08:34:42 AM
If the road changes from freeway to expressway, the slow lane would need to switch from the left to the right.
I guess it would be instinctive, drivers would quickly figure out that the slow lane is the one with all the exits and entrances.
MA 2 in Fitchburg? The cemetery on MA 128 in Peabody?
A hodgepodge of thoughts:
The Thruway EB between I-890 and Free I-90/I-87 (Exit 24): Exit 24 is a left off-ramp and commuters from Schenectady do plant themselves in the left lane no matter how slow they're travelling. It's a classic example of why left off-ramps are bad, no matter how much room you give them.
I-690 to I-481 NB is a left on-ramp. I don't think it is that problematic as is -- traffic volumes are low enough to allow for poor mergers that don't speed up enough. But, I believe this will also be addressed in Phase 1 of the I-81 project.
There's also that left on-ramp from Maryland House (I believe) onto I-95 SB that can be a disaster if you get behind someone not willing match the speed of traffic. It's built long enough, but if you get stuck behind someone scared to go over 55, it's still harrowing.
Quote from: kernals12 on February 27, 2021, 08:40:12 AM
Quote from: kphoger on February 27, 2021, 08:24:11 AM
Quote from: Occidental Tourist on February 26, 2021, 11:30:28 PM
And imagine how much less right of way would be needed to expand freeways at crossroads.
Now imagine the headache of expanding the ramps, though.
But since it would be a SPUI, the ramps would have more capacity and would be less likely to need expansion.
In which case, the ramps would be
initially constructed at lower capacity, and therefore would still need to be expanded with enough increase in traffic. It's not like departments would simply construct ramps that are way over capacity for no good reason.
Quote from: kernals12 on February 27, 2021, 08:50:42 AM
Quote from: GaryV on February 27, 2021, 08:34:42 AM
If the road changes from freeway to expressway, the slow lane would need to switch from the left to the right.
I guess it would be instinctive, drivers would quickly figure out that the slow lane is the one with all the exits and entrances.
1. It would not be instinctive.
2. All that weaving would be utter chaos.
Quote from: 1 on February 27, 2021, 08:53:27 AM
Quote from: kernals12 on February 27, 2021, 08:50:42 AM
Quote from: GaryV on February 27, 2021, 08:34:42 AM
If the road changes from freeway to expressway, the slow lane would need to switch from the left to the right.
I guess it would be instinctive, drivers would quickly figure out that the slow lane is the one with all the exits and entrances.
MA 2 in Fitchburg? The cemetery on MA 128 in Peabody?
Sorry, I don't know what you're talking about
Quote from: kernals12 on February 27, 2021, 09:10:27 AM
Quote from: 1 on February 27, 2021, 08:53:27 AM
Quote from: kernals12 on February 27, 2021, 08:50:42 AM
Quote from: GaryV on February 27, 2021, 08:34:42 AM
If the road changes from freeway to expressway, the slow lane would need to switch from the left to the right.
I guess it would be instinctive, drivers would quickly figure out that the slow lane is the one with all the exits and entrances.
MA 2 in Fitchburg? The cemetery on MA 128 in Peabody?
Sorry, I don't know what you're talking about
Both cases I'm talking about have one or two at-grades in the middle of a freeway. If all the entrances and exits were on the left, and the right was the fast lane, you would suddenly have people getting on and off in the fast lane.
This guy does make some good points. Though when he mentions the cost difference and space difference, does he factor in that the through carrigeways need to be a lot farther apart? Elimination of weaving within the interchange is kind of a moot point because unfamiliar drivers aren't expecting the left merge.
There are certain pros to left exits over huge flyovers, for sure. But overall, all right exits is better IMO. Plus, SPUIs are better than DDIs anyways. :-D
Quote from: 1 on February 27, 2021, 09:13:01 AM
Quote from: kernals12 on February 27, 2021, 09:10:27 AM
Quote from: 1 on February 27, 2021, 08:53:27 AM
Quote from: kernals12 on February 27, 2021, 08:50:42 AM
Quote from: GaryV on February 27, 2021, 08:34:42 AM
If the road changes from freeway to expressway, the slow lane would need to switch from the left to the right.
I guess it would be instinctive, drivers would quickly figure out that the slow lane is the one with all the exits and entrances.
MA 2 in Fitchburg? The cemetery on MA 128 in Peabody?
Sorry, I don't know what you're talking about
Both cases I'm talking about have one or two at-grades in the middle of a freeway. If all the entrances and exits were on the left, and the right was the fast lane, you would suddenly have people getting on and off in the fast lane.
In a world where left hand ramps were the norm, then I'm sure they would've designed those differently.
Quote from: kernals12 on February 27, 2021, 09:21:45 AM
In a world where left hand ramps were the norm
So, Australia?
Quote from: The article:4. Safety — The new Highway Safety Manual suggests that there is likely to be 49% more crashes with left ramps compared to other ramps. Avoiding left side ramps would seem to be a safe choice.
Might as well stop reading right there. :banghead:
I don't know about you, but I feel unsafe merging from the left because my view of the traffic stream I'm merging into is much more restricted looking to the right than it is looking to the left, and it's utterly unsurprising to me that accident statistics confirm that my discomfort is warranted. The same is true to a lesser degree with changing lanes in a rightward direction, though that's usually mitigated by having more time and distance to make the maneuver
and a speed advantage over the vehicles to the right.
Quote from: thspfc on February 27, 2021, 09:23:30 AM
Quote from: kernals12 on February 27, 2021, 09:21:45 AM
In a world where left hand ramps were the norm
So, Australia?
The way the OP has taken this thread strongly suggests maybe it belongs in "Fictional Highways," because that's what "a world where left hand ramps were the norm" is (also note his use of the subjunctive "were" underscoring the condition contrary to fact). It didn't necessarily start out that way because he cited an article whose author suggests that having a mixture of left- and right-side ramps wouldn't be the bad thing most of us believe it is, which is an interesting theory, but it's clear that the OP is, as usual, desperate to push a different theory from that on us. There is zero chance, none whatsoever, that left-side ramps will ever be "the norm" in the USA, and there's even less chance of all our roads being torn up and rebuilt (at huge expense and disruption) because some kid in Massachusetts thinks they're designed incorrectly.
If you then take the OP's theory (which I highly doubt he actually believes) that left-side ramps should be the standard, then extrapolating that theory to Australia or the UK, or really any other country where you drive on the left (well, maybe not Samoa as I doubt they have freeways), would mean in those countries right-side ramps should be the standard.
Quote from: thspfc on February 27, 2021, 09:15:37 AM
This guy does make some good points. Though when he mentions the cost difference and space difference, does he factor in that the through carrigeways need to be a lot wider? Elimination of weaving within the interchange is kind of a moot point because unfamiliar drivers aren't expecting the left merge.
There are certain pros to left exits over huge flyovers, for sure. But overall, all right exits is better IMO. Plus, SPUIs are better than DDIs anyways. :-D
The carriageways only needs to be wider at interchanges; that'll be no different than the right of way needed for right side ramps. Between interchanges, the roadways can bump up against each other with only a guardrail or Jersey Barrier separating them.
Quote from: 1995hoo on February 27, 2021, 10:47:41 AM
Quote from: thspfc on February 27, 2021, 09:23:30 AM
Quote from: kernals12 on February 27, 2021, 09:21:45 AM
In a world where left hand ramps were the norm
So, Australia?
The way the OP has taken this thread strongly suggests maybe it belongs in "Fictional Highways," because that's what "a world where left hand ramps were the norm" is (also note his use of the subjunctive "were" underscoring the condition contrary to fact). It didn't necessarily start out that way because he cited an article whose author suggests that having a mixture of left- and right-side ramps wouldn't be the bad thing most of us believe it is, which is an interesting theory, but it's clear that the OP is, as usual, desperate to push a different theory from that on us. There is zero chance, none whatsoever, that left-side ramps will ever be "the norm" in the USA, and there's even less chance of all our roads being torn up and rebuilt (at huge expense and disruption) because some kid in Massachusetts thinks they're designed incorrectly.
If you then take the OP's theory (which I highly doubt he actually believes) that left-side ramps should be the standard, then extrapolating that theory to Australia or the UK, or really any other country where you drive on the left (well, maybe not Samoa as I doubt they have freeways), would mean in those countries right-side ramps should be the standard.
Do you not understand the idea of hypothetical? Here, I'll help you (https://www.merriam-webster.com/dictionary/hypothetical)
QuoteDefinition of hypothetical
: involving or being based on a suggested idea or theory : being or involving a hypothesis :
Quote from: kphoger on February 27, 2021, 09:07:50 AM
Quote from: kernals12 on February 27, 2021, 08:40:12 AM
Quote from: kphoger on February 27, 2021, 08:24:11 AM
Quote from: Occidental Tourist on February 26, 2021, 11:30:28 PM
And imagine how much less right of way would be needed to expand freeways at crossroads.
Now imagine the headache of expanding the ramps, though.
But since it would be a SPUI, the ramps would have more capacity and would be less likely to need expansion.
In which case, the ramps would be initially constructed at lower capacity, and therefore would still need to be expanded with enough increase in traffic. It's not like departments would simply construct ramps that are way over capacity for no good reason.
Quote from: kernals12 on February 27, 2021, 08:50:42 AM
Quote from: GaryV on February 27, 2021, 08:34:42 AM
If the road changes from freeway to expressway, the slow lane would need to switch from the left to the right.
I guess it would be instinctive, drivers would quickly figure out that the slow lane is the one with all the exits and entrances.
1. It would not be instinctive.
2. All that weaving would be utter chaos.
Most freeway ramps are one lane. It's not possible to have them be less than one lane, so the capacity would be higher.
Quote from: kernals12 on February 27, 2021, 11:35:28 AM
Quote from: 1995hoo on February 27, 2021, 10:47:41 AM
Quote from: thspfc on February 27, 2021, 09:23:30 AM
Quote from: kernals12 on February 27, 2021, 09:21:45 AM
In a world where left hand ramps were the norm
So, Australia?
The way the OP has taken this thread strongly suggests maybe it belongs in "Fictional Highways," because that's what "a world where left hand ramps were the norm" is (also note his use of the subjunctive "were" underscoring the condition contrary to fact). It didn't necessarily start out that way because he cited an article whose author suggests that having a mixture of left- and right-side ramps wouldn't be the bad thing most of us believe it is, which is an interesting theory, but it's clear that the OP is, as usual, desperate to push a different theory from that on us. There is zero chance, none whatsoever, that left-side ramps will ever be "the norm" in the USA, and there's even less chance of all our roads being torn up and rebuilt (at huge expense and disruption) because some kid in Massachusetts thinks they're designed incorrectly.
If you then take the OP's theory (which I highly doubt he actually believes) that left-side ramps should be the standard, then extrapolating that theory to Australia or the UK, or really any other country where you drive on the left (well, maybe not Samoa as I doubt they have freeways), would mean in those countries right-side ramps should be the standard.
Do you not understand the idea of hypothetical? Here, I'll help you (https://www.merriam-webster.com/dictionary/hypothetical)
QuoteDefinition of hypothetical
: involving or being based on a suggested idea or theory : being or involving a hypothesis :
Ergo, "Fictional Highways." Keep digging that hole, sonny. Maybe someday you'll reach China.
Quote from: 1995hoo on February 27, 2021, 12:36:23 PM
Quote from: kernals12 on February 27, 2021, 11:35:28 AM
Quote from: 1995hoo on February 27, 2021, 10:47:41 AM
Quote from: thspfc on February 27, 2021, 09:23:30 AM
Quote from: kernals12 on February 27, 2021, 09:21:45 AM
In a world where left hand ramps were the norm
So, Australia?
The way the OP has taken this thread strongly suggests maybe it belongs in "Fictional Highways," because that's what "a world where left hand ramps were the norm" is (also note his use of the subjunctive "were" underscoring the condition contrary to fact). It didn't necessarily start out that way because he cited an article whose author suggests that having a mixture of left- and right-side ramps wouldn't be the bad thing most of us believe it is, which is an interesting theory, but it's clear that the OP is, as usual, desperate to push a different theory from that on us. There is zero chance, none whatsoever, that left-side ramps will ever be "the norm" in the USA, and there's even less chance of all our roads being torn up and rebuilt (at huge expense and disruption) because some kid in Massachusetts thinks they're designed incorrectly.
If you then take the OP's theory (which I highly doubt he actually believes) that left-side ramps should be the standard, then extrapolating that theory to Australia or the UK, or really any other country where you drive on the left (well, maybe not Samoa as I doubt they have freeways), would mean in those countries right-side ramps should be the standard.
Do you not understand the idea of hypothetical? Here, I'll help you (https://www.merriam-webster.com/dictionary/hypothetical)
QuoteDefinition of hypothetical
: involving or being based on a suggested idea or theory : being or involving a hypothesis :
Ergo, "Fictional Highways." Keep digging that hole, sonny. Maybe someday you'll reach China.
I think we're all getting a little tired of kernals12's contrarian posts. He went on a two-week tirade in the weather board about how global warming is good because it makes it warmer in Boston in the winter. All of his posts are just looking for a negative reaction.
This whole line of discussion assumes that every single interchange along a stretch of freeway can be a SPUI /slash/ tight diamond interchange.
Traffic volumes warrant a cloverleaf somewhere? Too bad!
Railroad along a crossroad necessitates a ParClo? Too bad!
Stoplight synchronization along a crossroad destroyed by a SPUI? Too bad!
Because, unless ALL of the interchanges can have left-side ramps, the right lane cannot simply be "the fast lane".
In a fit of boredom, I created this lefthand cloverleaf. It's more or less workable, except that the footprint is enormous, about four times the size of a regular cloverleaf.
Behold:
(https://i.imgur.com/GwNK2Do.png)
Also, now that I think about it, the loop ramps are arguably unnecessary, in that you can just do three straight ramps in a row to end up in the right direction (much like you can do three loop ramps in a row on a regular cloverleaf), but that doesn't really save any space.
Quote from: CtrlAltDel on February 27, 2021, 05:03:30 PM
In a fit of boredom, I created this lefthand cloverleaf. It's more or less workable, except that the footprint is enormous, about four times the size of a regular cloverleaf.
Behold:
(https://i.imgur.com/GwNK2Do.png)
It also looks like the weaving on left hand turns is even worse than on a normal cloverleaf.
Here's a better low cost interchange with left hand ramps
(https://i.imgur.com/o4lOYLf.jpg)
That one has both left and right, so it fails k's theory that all ramps could be on the left. (could be - hypothetical - happy?)
Quote from: kphoger on February 27, 2021, 03:36:02 PM
This whole line of discussion assumes that every single interchange along a stretch of freeway can be a SPUI /slash/ tight diamond interchange.
Traffic volumes warrant a cloverleaf somewhere? Too bad!
Railroad along a crossroad necessitates a ParClo? Too bad!
Stoplight synchronization along a crossroad destroyed by a SPUI? Too bad!
Because, unless ALL of the interchanges can have left-side ramps, the right lane cannot simply be "the fast lane".
This sort of follows the point I was trying to make about how the original post, and the blog entry linked there, envisioned BOTH left- AND right-side exits:
Quote from: kernals12 on February 26, 2021, 08:36:29 AM
Left hand ramps are frowned upon by highway engineers due to the safety problem posed by having people merge into the fast lane when they're entering the freeway, but in 2011, Gilbert Chlewicki, the man who invented the diverging diamond interchange (or rather reinvented it after France tried it and gave up on it in the 70s, decided to defend the undefendable.
(https://divergingdiamond.com/blog/reconsidering-left-side-ramps-on-freeways/)
Quote
....
Lane Balancing — When all ramps are on the right side of the highway, it requires a heavier load of traffic in the right lanes of the highway. When an interchange has a high volume of traffic using the ramps, this can cause delays on the entire highway due to the heavy weaving needed that slows traffic down. When left ramps are introduced, traffic can be more evenly distributed among all the lanes of the highway, which can improve overall traffic flow.
....
....
Think about it for a minute. kernals12 has been going on about having all left-side exits, or making them the predominant style. But wouldn't that just mean you'd have the same "imbalance problem" theorized in the paragraph quoted above, just on the left instead of on the right? The blog writer clearly envisions a
mix of ramps on both sides so as to "balance" the traffic load.
I think that idea is more interesting as a discussion topic than kernals12's attempt to change the focus. As a practical matter, though, to some degree I kind of like having more of the traffic concentrated to one side if I don't want to exit. For example, back in the 1990s, before the Springfield Interchange in Virginia was rebuilt, if I were headed from Fairfax to Alexandria on the Beltway, I could get all the way over to the left and I'd bypass the long queue of crawling or stopped traffic over to the right that was trying to head to southbound I-95. The "imbalance" was a good thing as far as I was concerned. And as I said earlier in the thread, if there were a lot of exits on both sides and the highway had only two lanes in each direction, there would be no real "passing lane," and that would be a problem.
Quote from: CtrlAltDel on February 27, 2021, 05:03:30 PM
In a fit of boredom, I created this lefthand cloverleaf. It's more or less workable, except that the footprint is enormous, about four times the size of a regular cloverleaf.
Behold:
(https://i.imgur.com/GwNK2Do.png)
Also, now that I think about it, the loop ramps are arguably unnecessary, in that you can just do three straight ramps in a row to end up in the right direction (much like you can do three loop ramps in a row on a regular cloverleaf), but that doesn't really save any space.
Could you draw a stack interchange with left handed ramps?
Anyone who is in favor of left-sided ramps probably failed the entire concept of walking to the ride side of the hallway since Kindergarten.
Quote from: kernals12 on February 27, 2021, 09:32:09 PM
Could you draw a stack interchange with left handed ramps?
Here you go. You could probably shave a bit more space from the middle if you wanted to.
(https://i.imgur.com/9OX090Z.png)
Quote from: jeffandnicole on February 27, 2021, 11:09:46 PM
... the ride side of the hallway since Kindergarten.
You had a ride side? Was it kind of like the "Stand/Walk" markings you see in airports? :wow:
Must have been some kind of experimental model school. :-D
Quote from: CtrlAltDel on February 27, 2021, 11:44:19 PM
Quote from: kernals12 on February 27, 2021, 09:32:09 PM
Could you draw a stack interchange with left handed ramps?
Here you go. You could probably shave a bit more space from the middle if you wanted to.
(https://i.imgur.com/9OX090Z.png)
I was assuming you'd have flyovers for the left turns, like in the Lodge-Ford Interchange in Detroit and then your right turns would branch off of those connecting to a flyover going in the opposite direction.
Quote from: jeffandnicole on February 27, 2021, 11:09:46 PM
Anyone who is in favor of left-sided ramps probably failed the entire concept of walking to the ride side of the hallway since Kindergarten.
But if I wanted to turn left in Kindergarten, I wouldn't go to the right and "fly over" to head left. :sombrero:
That being said, I do think that there are times where things get "over engineered" to eliminate left hand exits. Whether or not the cost of that engineering makes sense is unknown to me.
Quote from: SEWIGuy on February 28, 2021, 09:12:53 AM
Quote from: jeffandnicole on February 27, 2021, 11:09:46 PM
Anyone who is in favor of left-sided ramps probably failed the entire concept of walking to the ride side of the hallway since Kindergarten.
But if I wanted to turn left in Kindergarten, I wouldn't go to the right and "fly over" to head left. :sombrero:
That being said, I do think that there are times where things get "over engineered" to eliminate left hand exits. Whether or not the cost of that engineering makes sense is unknown to me.
This thought process immediately shows that people only care about themselves, not the overall flow of traffic. That's where engineering comes in.
In terms of my example, sure, if you want to take an exaggerated view of things, you're right.
But, people should keep to the right when walking. When people stop at their lockers and such, the flow of traffic moves towards the center of the hallway. But what happens when a few people stop to talk in the middle of the hallway? Congestion ensues. People have to walk around them, which entails getting close to those already stopped at their lockers.
If you don't want to use a school as an example, think of a supermarket where people stop their carts in the middle. Or a walking trail, where people stop to talk. In each case, the ones stopped (just a few) are causing the congestion, and the others have to figure a way around.
To continue on, when you believe things are over engineered, again, you are looking at a very small area, thru horse blinders, without considering the overall impact of traffic flow. You are also very unaware of all the costs of highway construction. Why even bother with interchanges? To be cheaper, all roadways should just have intersections. Traffic lights cost money, so just use stop signs. Wider roadways cost money, so make them one lane each way. Don't bother with shoulders. Eliminate signage. Drainage is a huge cost of roadway building, so just let the roadways and surrounding infrastructure flood. The base of the roadway goes a foot or more down below the surface. 2 inches of asphalt would definitely reduce the costs.
So the cost to build something is an important part of a project, but it's by far not the only thing. If it costs $10 million to build something that isn't expected to congest for 20 years, or $1 million to build something that will instantly congest, transportation departments would rather spend the $10 million even though it's more money.
Quote from: jeffandnicole on February 28, 2021, 12:06:06 PM
Quote from: SEWIGuy on February 28, 2021, 09:12:53 AM
Quote from: jeffandnicole on February 27, 2021, 11:09:46 PM
Anyone who is in favor of left-sided ramps probably failed the entire concept of walking to the ride side of the hallway since Kindergarten.
But if I wanted to turn left in Kindergarten, I wouldn't go to the right and "fly over" to head left. :sombrero:
That being said, I do think that there are times where things get "over engineered" to eliminate left hand exits. Whether or not the cost of that engineering makes sense is unknown to me.
This thought process immediately shows that people only care about themselves, not the overall flow of traffic. That's where engineering comes in.
In terms of my example, sure, if you want to take an exaggerated view of things, you're right.
But, people should keep to the right when walking. When people stop at their lockers and such, the flow of traffic moves towards the center of the hallway. But what happens when a few people stop to talk in the middle of the hallway? Congestion ensues. People have to walk around them, which entails getting close to those already stopped at their lockers.
If you don't want to use a school as an example, think of a supermarket where people stop their carts in the middle. Or a walking trail, where people stop to talk. In each case, the ones stopped (just a few) are causing the congestion, and the others have to figure a way around.
To continue on, when you believe things are over engineered, again, you are looking at a very small area, thru horse blinders, without considering the overall impact of traffic flow. You are also very unaware of all the costs of highway construction. Why even bother with interchanges? To be cheaper, all roadways should just have intersections. Traffic lights cost money, so just use stop signs. Wider roadways cost money, so make them one lane each way. Don't bother with shoulders. Eliminate signage. Drainage is a huge cost of roadway building, so just let the roadways and surrounding infrastructure flood. The base of the roadway goes a foot or more down below the surface. 2 inches of asphalt would definitely reduce the costs.
So the cost to build something is an important part of a project, but it's by far not the only thing. If it costs $10 million to build something that isn't expected to congest for 20 years, or $1 million to build something that will instantly congest, transportation departments would rather spend the $10 million even though it's more money.
I mean I said I didn't fully understand the engineering involved so...
In a more suburban area, left lane exits (if put together with merge lanes from both directions) could lessen traffic problems with the intersecting street by having one point of entry/exit with traffic control rather than on each side of the overpass or underpass as the case warranted.
Quote from: jeffandnicole
Anyone who is in favor of left-sided ramps probably failed the entire concept of walking to the ride side of the hallway since Kindergarten.
Quote from: jeffandnicole
This thought process immediately shows that people only care about themselves, not the overall flow of traffic.
You're making a lot of smug assumptions about people's underlying psychological traits based on how they discuss or advocate for a particular roadway configuration. Has drawing broad-based correlations as to a person's likely behavior based on seemingly unrelated thoughts and opinions served you well in life? Do you see someone eating a burrito at a restaurant and reach valid conclusions about their political leanings, ecological views, or charitable habits? If I see someone driving a red car, what conclusions should I make about their bathroom hygiene or whether they prefer action movies or dramas?
If you're going to accuse people of being selfish or lacking manners because they disagree with your position
about how a roadway should be designed, you may be better served on Twitter than this board. That sort of jackassery is encouraged there.
Think about the safety aspect. It is much easier to merge left than it is to merge right, with the driver being situated closer to the left-side mirror of the vehicle and therefore able to see and judge other traffic better. Doing away with right-side merge lanes would contribute to at least a noticeable increase in yearly traffic crashes, in my opinion.
And, a quote from Wikipedia's article on Texas' High Five interchange:
Quote
It replaces the antiquated three-level, modified cloverleaf interchange built in the 1960s that caused a severe bottleneck by narrowing US 75 down to two lanes at the junction of the two highways. The looped ramps of the cloverleaf forced motorists to slow down drastically, backing up traffic. Left-hand exits contributed to the congestion.
Quote from: jeffandnicole on February 28, 2021, 12:06:06 PM
But, people should keep to the right when walking. When people stop at their lockers and such, the flow of traffic moves towards the center of the hallway. But what happens when a few people stop to talk in the middle of the hallway? Congestion ensues. People have to walk around them, which entails getting close to those already stopped at their lockers.
Do they actually teach/enforce "keep to the right in hallways" in school in other states? In Oklahoma, it's just a damn mosh pit all the way through high school. And of course, nothing changes when you go to the grocery store or the casino or anywhere else people congregate and there's aisles or other hallway-type spaces, because nobody was ever taught any better. Sigh.
That was certainly never taught when I was in school, other than perhaps in my first elementary school when they wanted everyone to stay to the right side going up and down the stairs (that went out the door whenever there was a fire drill, of course).
Quote from: Scott5114 on February 28, 2021, 05:02:36 PM
Quote from: jeffandnicole on February 28, 2021, 12:06:06 PM
But, people should keep to the right when walking. When people stop at their lockers and such, the flow of traffic moves towards the center of the hallway. But what happens when a few people stop to talk in the middle of the hallway? Congestion ensues. People have to walk around them, which entails getting close to those already stopped at their lockers.
Do they actually teach/enforce "keep to the right in hallways" in school in other states? In Oklahoma, it's just a damn mosh pit all the way through high school. And of course, nothing changes when you go to the grocery store or the casino or anywhere else people congregate and there's aisles or other hallway-type spaces, because nobody was ever taught any better. Sigh.
I was never taught it explicitly...but it was one of those things that you'd learn pretty quickly. I don't think anything below high school had any rhyme or reason, but when I started high school I learned to keep right in the halls very quickly. If you happened to find yourself on the left side, you'd be constantly bumping into older students who would give you weird looks. Most freshmen would figure it out after a week.
My high school wasn't busy enough for hallway traffic flow to register as a concern, but I tried to keep right when I could, just like I do in any other hallway or aisle or trail or bike path. The concept of KRETP isn't just for roads.
Quote from: Occidental Tourist on February 28, 2021, 03:52:11 PM
If I see someone driving a red car, what conclusions should I make about their bathroom hygiene or whether they prefer action movies or dramas?
Action movies.
Also...
Quote from: JoePCool14 on February 26, 2021, 09:49:29 AM
Quote from: 1995hoo on February 26, 2021, 09:21:54 AM
I recognize he's not talking solely about DDIs and is instead talking about left-side ramps in general, but in the DDI context I would argue that left-side ramps in a standard DDI are a different circumstance anyway because the "fast lane" (more properly the "passing lane") is not an issue, as the road with the left-side ramps is, by definition, not going to be a freeway due to there being traffic lights at either end of the DDI where the directions cross over. If there were to be a modified DDI that used grade-separated crossovers to eliminate the two traffic lights, that might be a different scenario.
I didn't click your link (don't have time), but one problem I've noted with left-side ramps in general-purpose lanes (as opposed to managed lanes, which generally carry fewer vehicles) is that it exacerbates the incredibly annoying tendency some people have to camp in the left lane. "I want to exit on the left six miles down the road, so I'm going to get over to the left lane immediately." Ugh.
I can definitely see that being a problem. If you don't give enough advanced noticed, it's confusing. But if you give too much advanced notice, people camp in the left lane. As with all things there's never a one size fits all solution.
I will say that in urban and suburban areas, for instance the Tri-State in Chicagoland, there's so much traffic that all lanes are filled with cars. Yes, the slower traffic generally stays on the right, but it's rare to get an open left lane. In that instance, a left exit with campers wouldn't make things much worse than they already are.
You hit on a very good point about urban areas having so much traffic the left lane isn't really a good fast lane. Here in Houston we don't have very many left exits, just a couple on IH 45 downtown and at IH 10 and IH 69 but there's so much traffic everywhere that a left exit just would not affect traffic in any significant way.
Part of the reason they want to redo 45 is to get rid of the left exits for McKinney street and Allen parkway.
Quote from: jeffandnicole on February 28, 2021, 12:06:06 PM
Why even bother with interchanges? To be cheaper, all roadways should just have intersections. Traffic lights cost money, so just use stop signs. Wider roadways cost money, so make them one lane each way. Don't bother with shoulders. Eliminate signage. Drainage is a huge cost of roadway building, so just let the roadways and surrounding infrastructure flood. The base of the roadway goes a foot or more down below the surface. 2 inches of asphalt would definitely reduce the costs.
Why even build roads at all? Just drive wherever you want. :-D
Quote from: 1995hoo on February 26, 2021, 09:21:54 AM
I recognize he's not talking solely about DDIs and is instead talking about left-side ramps in general, but in the DDI context I would argue that left-side ramps in a standard DDI are a different circumstance anyway because the "fast lane" (more properly the "passing lane") is not an issue, as the road with the left-side ramps is, by definition, not going to be a freeway due to there being traffic lights at either end of the DDI where the directions cross over. If there were to be a modified DDI that used grade-separated crossovers to eliminate the two traffic lights, that might be a different scenario.
I didn't click your link (don't have time), but one problem I've noted with left-side ramps in general-purpose lanes (as opposed to managed lanes, which generally carry fewer vehicles) is that it exacerbates the incredibly annoying tendency some people have to camp in the left lane. "I want to exit on the left six miles down the road, so I'm going to get over to the left lane immediately." Ugh.
I'll trust The Eagles over you thank you very much.
Quote from: kernals12 on March 06, 2021, 07:51:59 PM
Quote from: 1995hoo on February 26, 2021, 09:21:54 AM
I recognize he's not talking solely about DDIs and is instead talking about left-side ramps in general, but in the DDI context I would argue that left-side ramps in a standard DDI are a different circumstance anyway because the "fast lane" (more properly the "passing lane") is not an issue, as the road with the left-side ramps is, by definition, not going to be a freeway due to there being traffic lights at either end of the DDI where the directions cross over. If there were to be a modified DDI that used grade-separated crossovers to eliminate the two traffic lights, that might be a different scenario.
I didn't click your link (don't have time), but one problem I've noted with left-side ramps in general-purpose lanes (as opposed to managed lanes, which generally carry fewer vehicles) is that it exacerbates the incredibly annoying tendency some people have to camp in the left lane. "I want to exit on the left six miles down the road, so I'm going to get over to the left lane immediately." Ugh.
I'll trust The Eagles over you thank you very much.
Are you saying that life in the fast lane surely made you lose your mind?
Cause that'd explain a lot.
Another one: in Arlington, Virginia, they plan on converting the current US 1 diamond interchange into one with left hand ramps (https://arlingtonva.s3.amazonaws.com/wp-content/uploads/sites/5/2014/03/sprc_Jul3012_SectorPlan_CrystalCityPO.pdf)
When I say it saves a lot of space, I'm not kidding
(https://i.imgur.com/xbn0G8k.png)
(https://i.imgur.com/KlzTkly.jpg)
Looks like Connecticut's love affair with left hand ramps is still strong. They're building a new one on I-91 at the Charter Oak Bridge. It replaces a steep 1 lane right hand exit with a long 2 lane left hand exit.